Chapter 9. Animal Growth and Carcass Compositionusers.tamuk.edu/kfsdl00/Chapter 9-1419.pdfAnimal Growth and Carcass Composition ... meat animals -- Live weight, BCS, loin eye ... and

Chapter 9. Animal Growth

and Carcass Composition

I. ANIMAL GROWTH A. Chronological vs. physiological

1. Chronological growth – the increase in size or body function due to an animal growing older.

2. Physiological growth

– the increase in size or

body function due to

increases in tissue and

organ growth and

development.



I. ANIMAL GROWTH A. Chronological vs. physiological

3. Terms relating to growth:

a. hypertrophy –

b. hyperplasia –

c. anabolism -

d. catabolism -

Chapter 9. Animal Growth and Carcass Composition

B. Measures of Growth 1. Measurements can be

objective or subjective, varies by the intended use of the animal

a.) meat animals -- Live weight, BCS, loin eye

area, back fat thickness

Body condition score

http://av.rds.yahoo.com/_ylt=A9ibyJ8xSFZDOMMANVxvCqMX;_ylu=X3oDMTBvMmFkM29rBHBndANhdl9pbWdfcmVzdWx0BHNlYwNzcg--/SIG=12bobrrk9/EXP=1129814449/**http%3a//www.sfktech.com/products/measuring.ultrafom.html

http://av.rds.yahoo.com/_ylt=A9ibyKx6SFZDCGEApR9vCqMX;_ylu=X3oDMTBvMmFkM29rBHBndANhdl9pbWdfcmVzdWx0BHNlYwNzcg--/SIG=1294nc7dt/EXP=1129814522/**http%3a//www.mccalibangus.com/Ultrasound%2520Images.htm

https://pubs.ext.vt.edu/400/400-795/400-795.html



b.) breeding animals: ability to produce offspring.

- - Live weight, age at first estrus, and testicle size

c.) other specialty products - - milk, wool, eggs

Figure 1

Scrotal circumference is measured by

holding the testicles to the bottom of the

scrotal sack and placing the tape around the

widest point (minimum of 30 cm).

Figure 2

Pelvic area is measured by taking

the product of vertical and

horizontal measurements (13 X 14

cm = 175 cm2).



c.) work animals:

Body weight

Agility/Speed

Endurance

Cutting ability

Pulling power

Rate of learning

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2. Average Daily Gain (ADG) – measurement of growth rate.

last weight – initial weight

ADG =

ending time – begin time

- commonly used measurement of meat animals.


Other Growth Measures:

For example:

Body weight at

52 days of age in

broiler chickens/

Number of days to

230 lbs in swine


and Carcass Composition C. The Growth Curve

1. Commonly represented as the gain in

weight over time.



2. Livestock growth curve

generally separated into

3 phases:

a.) prenatal: the increase

in weight from

conception to birth

(i.e., zygote, embryo, &

fetal phase)

Factors: AOD, uterine

quality, and gender of

fetus

What is a hinny?

http://www.maulesel.info/what_is_a_hinny.html



Heterospermic natural matings of NZW

doe to large, medium, and small breeds

of buck (Flemish Giant, Californian, and

Florida White).



2. Livestock growth curve generally separated

into 3 phases:

b.) preweaning: birth to weaning

- age/body size of dam

- milk production

- gender

- no. of teats/litter size

(>14 teats in swine;

no > 9 kits in rabbits)

“cross-fostering”



c.) postweaning: weaning to harvest

- affected by pre-

weaning background

- genetics

- gender

- environment

- nutrition



D. Factors affecting growth

1. Hormonal growth

a.) Hormones are chemical messengers.

b.) Hormones coordinate growth and

development of body tissues structures,

and organs – help ensure “homeostasis”

Homeostasis:

Is the property of a system that regulates its

internal environment and tends to maintain a

stable, relatively constant condition of properties

such as temperature or pH (Wikipedia, 2012).



c.) Hormone secretion:

endocrine glands

circulation

target tissue

response


d.) types of growth related hormones:

1. Somatotropin (ST, “Growth Hormone”)

secreted from the anterior

pituitary

regulates development

of bone and muscle

increases milk yield

bST increases milk yield by

repartitioning nutrients from fat

to the mammary tissue


pST increases meat yield by

increasing protein deposition by 30%

and decreases fat by 45%

2. Thyroxine

secreted by the thyroid gland

regulates basal metabolic rate

too little impairs bone and

muscle growth –

“hypothyroidism”


too much thyroxine results in

less nutrient utilization due to

high metabolic rate –

“hyperthyroidism”

exogenous hormone used to

increase feathering in poultry,

wool and milk production in sheep

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and Carcass Composition 3. Androgens

the hormone, testosterone, is involved in secondary sexual development in males

testosterone increases bone and muscle growth in males and females

testosterone is a

major androgen that is produced in the testes and in the adrenal glands

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4. Estrogens

secreted from the ovaries

increases muscle growth in ruminants and fat deposition in poultry

slows growth of these tissue types in other species

http://www.altavista.com/r?ck_sm=223661ca&rpos=11&oid=8571a7ed4fddd54e&rpge=1&ref=200090096&r=http%3A%2F%2Fwww.iso.gmu.edu%2F%7Ecpatton%2Fchem350.html

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5. Glucocorticoids

secreted from the adrenal glands

involved in stress and inflammation

stimulates feeding

(increase appetite)

repartitions nutrients

(to produce energy for growth)



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Chapter 9. Animal Growth and

Carcass Composition E. General Growth Factors:

1. Genetics

a.) genetic predetermination at conception of animal’s body size and growth rate

b.) preweaning growth largely dependent on milk availability, but postweaning growth gain is largely dependent on the animal’s genetics

c.) genetic or hormonal imbalance can harm growth potential



2. Milk Production

In beef cattle, about

50% of variation in

weaning weights of

calves is due to

differences among

cows in milk

production.

In rabbits, it is said

that the litter is “made

in the nestbox”.



3. Gender

a.) androgens vs. estrogens

males grow faster than females

differences are

larger in cattle,

goats, and sheep

than in swine

Belgian Blue Bulls

http://belgianblueinternational.com/

http://www.animationlibrary.com/a-l/?n=image.php3&image_id=4639

https://www.youtube.com/watch?v=EKs_Rjhmlts



4. Nutrition

a.) diet affects immediate and subsequent growth traits

too much = fat deposition = decreased bone and organ growth and development

b.) compensatory gain



Compensatory gain

a.) very rapid growth when an animal on a nutrient poor diet switched to a nutrient rich diet


Carcass Composition 5. Antibiotics/Feed Additives/Implants

reduce incidence of disease

increase growth and nutrient

efficiency

alter rumen micro-organisms

which may improve

nutrient utilization

http://www.ralgro.com/



6. Physical environment

a.) shelter, flooring, cage size,

population density, sounds,

and climate affect growth

7. Management

a.) animal care and well-being




II. Carcass Composition

A. 3 main constituents

1. bone muscle fat

a.) total amount of increase or change

as growth occurs.

b.) proportion of each constituent

will differ

Younger animals > bone & muscle

than older animals > fat

Real-Time Ultrasound

Evaluation of Carcass

Traits

https://www.gov.mb.ca/agriculture/livestock/production/beef/real-time-ultrasound-evaluation-of-carcass-traits.html






Carcass Composition

c.) rate of tissue proportion

changes depends on:

species

breed

animal type

gender

diet

age


Documents

Chapter 9. Animal Growth and Carcass Compositionusers.tamuk.edu/kfsdl00/Chapter 9-1419.pdfAnimal Growth and Carcass Composition ... meat animals -- Live weight, BCS, loin eye ... and